Low temperature high reliability alloy for solder hierarchy

1. A lead-free, antimony-free solder alloy consisting of:

(a) from 1 to 4 wt. % silver

(b) from 0.5 to 6 wt. % bismuth

(c) from 7 to 12 wt % indium

(d) from 0.01 to 3 wt % copper

(e) from 0.005 to 1 wt. % of titanium

(f) one or more of the following elements

0 to 1 wt. % nickel

0 to 1 wt. % manganese

0 to 1 wt. % of rare earths, such as cerium

0 to 1 wt. % of chromium

0 to 1 wt. % germanium

0 to 1 wt. % of gallium

0 to 1 wt. % of cobalt

0 to 1 wt. % of iron

0 to 1 wt. % of aluminum

0 to 1 wt. % of phosphorus

0 to 1 wt. % of gold

0 to 1 wt. % of tellurium

0 to 1 wt. % of selenium

0 to 1 wt. % of calcium

0 to 1 wt. % of vanadium

0 to 1 wt. % of molybdenum

0 to 1 wt. % of platinum

0 to 1 wt. % of magnesium

(g) the balance tin, together with any unavoidable impurities.

2. The solder alloy according to claim 1 , wherein the alloy comprises from 1.2 to 3.8 wt. % silver.

3. The solder alloy according to claim 1 , wherein the alloy comprises from 2 to 4 wt. % silver, from 1 to 6 wt. % bismuth and from 7 to 10 wt. % indium.

4. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2 to 4 wt. % bismuth, from 7 to 9 wt. % indium and from 0.1 to 1.5 wt. % copper.

5. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 7 to 9 wt, % indium, from 0.3 to 0.8 wt. % copper and from 0.01 to 0.05 wt. % titanium.

6. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 7 to 9 wt. % indium, from 0.3 to 0.8 wt. % copper, from 0.005 to 0.05 wt. % titanium and from 0.005 to 1 wt. % germanium.

7. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 7 to 9 wt. % indium, from 0.3 to 0.7 wt. % copper, and from 0.001 to 0.03 wt. % germanium.

8. The solder alloy as claimed in claim 1 , wherein the alloy has a liquidus temperature of 215° C. or less.

9. A method of forming a solder joint comprising:

(i) providing two or more work pieces to be joined;

(ii) providing a solder alloy consisting of:

(a) from 1 to 4 wt. % silver

(b) from 0.5 to 6 wt. % bismuth

(c) from 7 to 12 wt. % indium

(d) from 0.01 to 3 wt. % or less of copper

(e) from 0.005 to 1 wt. % of titanium

(f) one or more of the following elements:

0 to 1 wt. % nickel

0 to 1 wt. % of titanium

0 to 1 wt. % manganese

0 to 1 wt. % of rare earths, such as cerium

0 to 1 wt. % of chromium

0 to 1 wt. % germanium

0 to 1 wt. % of gallium

0 to 1 wt. % of cobalt

0 to 1 wt. % of iron

0 to 1 wt. % of aluminum

0 to 1 wt. % of phosphorus

0 to 1 wt. % of gold

0 to 1 wt. % of tellurium

0 to 1 wt. % of selenium

0 to 1 wt. % of calcium

0 to 1 wt. % of vanadium

0 to 1 wt. % of molybdenum

0 to 1 wt. % of platinum

0 to 1 wt. % of magnesium

(g) the balance tin, together with any unavoidable impurities; and

(iii) heating the solder alloy in the vicinity of the work pieces to be joined.

10. A lead-free, antimony-free solder alloy consisting of:

(a) from 1 to 4 wt. % silver;

(b) from 0.5 to 6 wt. % bismuth;

(c) from 4.5 to 10 wt. % indium;

(d) from 0.01 to 3 wt. % copper;

(e) from 0.05 to 0.25 wt. % of nickel;

(f) from 0.01 to 0.05 wt. % manganese;

(g) optionally, from 0.005 to 1.0 wt. % phosphorus;

and the balance tin, together with any unavoidable impurities.

11. The solder alloy according to claim 10 , wherein the alloy comprises from 2 to 4 wt. % silver, from 2 to 4.5 wt. % bismuth, from 4.5 to 10 wt. % indium, from 0.1 to 1.5 wt. % of copper and from 0.05 to 0.25 wt. % of nickel.

12. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2 to 4 wt. % bismuth, from 5 to 8 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % of nickel.

13. The solder alloy according to claim 12 , wherein the alloy comprises from 2.5-3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 5.5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % nickel.

14. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 4 wt. % of silver, from 2.5 to 4 wt. % bismuth, from 5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % of nickel.

15. The solder alloy according to claim 14 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2.5 to 4 wt. % bismuth, from 5.5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % nickel.

16. The solder alloy according to claim 15 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2.5 to 4 wt. % bismuth, 6 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % nickel.

17. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2.5 to 4 wt. % bismuth, from 5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper, from 0.05 to 0.25 wt. % nickel and from 0.01 to 0.05 wt. % manganese.

18. The solder alloy according to claim 17 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 5.5 to 6.5 wt. indium, from 0.3 to 0.7 wt. % copper, from 0.05 to 0.25 wt. % nickel and from 0.005 to 0.05 wt. % manganese.

19. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 5.5 to 6.5 wt. % indium, from 0.3 to 0.8 wt. % copper, from 0.05 to 0.4 wt. % nickel, from 0.01 to 0.05 wt. % manganese and from 0.01 to 0.15 wt % phosphorous.

20. The solder alloy according to claim 10 comprising:

(a) 4.5 to 8 wt. % of indium; and

(b) from 0.005 to 1 wt. % phosphorus.

21. The solder alloy of claim 20 comprising from 2 to 4 wt. % silver, from 2 to 4 wt. % bismuth, from 0.1 to 0.8 wt. % copper and from 0.01 to 1 wt. % phosphorus.